While these are just a few uncommon causes of hives, there are many other factors that can be involved in your outbreaks. Other triggers include exercise, vibration, latex, pet dander, friction, or coming into contact with certain plants. Sometimes, hives are idiopathic in nature, meaning there is no known cause. Keeping a daily food, medicine, and activity journal may help you recognize your specific hive triggers. Work with an allergist to help you maintain an active life despite hives.